I-202 at high surface speed. ((U. S. Naval Historical Center), scanned from Polmar and Carpenter's "Submarines of the Imperial Japanese
Navy")

The Sen Taka (submarine, high speed), in high bursts of speed, could run faster submerged than on the surface for up to an hour. The only World War II submarine comparable in underwater speed to the I-201 class was the German Type XXI "Elektro-boote" class. The I-201 class had streamlined all-welded hulls, high capacity 4,192 cell batteries and electric motors that provided almost twice the horsepower of their German-designed diesel engines. The I-201 class were fitted with snorkels to allow cruising submerged on their diesels and recharging of their batteries while underwater. They carried 25-mm guns in retractable mounts to maintain streamlining. Eight boats were laid down, but only three were completed before the end of the war. None saw operational use.